1. Field
The general inventive concept relates to display apparatuses using a polymer dispersed liquid crystal, for example, to polymer dispersed display panels and apparatuses including quantum dots.
2. Description of the Related Art
Related art liquid crystal display (LCD) apparatuses include an optical shutter having a liquid crystal layer and polarization plates formed on each side of the liquid crystal layer. Related art LCD apparatuses also include a color filter. The color filter transmits light of a certain color from among light passing through the optical shutter. However, in such related art LCD apparatuses, about 50% of light is lost due to the two polarization plates, and about 33% of light is lost due to the color filter. Therefore, related art LCD apparatuses have a relatively low light usage efficiency of (e.g., about 10%).
Recently, a polymer dispersed liquid crystal (PDLC) device, which operates as an optical shutter without using two polarization plates has been commercialized. The PDLC device is a new type of LCD device and is formed by mixing a liquid crystal in a polymer and then hardening the polymer using ultraviolet (UV) rays. When the polymer is hardened by the UV rays, phases of the polymer and the liquid crystal are separated. As a result, a plurality of liquid crystal drops are confined in the hardened polymer. Therefore, the PDLC device has a structure in which a plurality of liquid crystal drops are dispersed in a hardened polymer layer.
In these PDLC devices, when no voltage is applied thereto, incident light is scattered at interfaces between the polymer and the liquid crystal drops due to a difference between refractive indexes of the polymer and the liquid crystal. Because many liquid crystal drops are dispersed in the polymer, the incident light is scattered repeatedly. Therefore, the PDLC device is opaque when no voltage is applied thereto. On the other hand, when a voltage is applied to the PDLC device, the liquid crystal drops are aligned in a constant direction, and the refractive index of the liquid crystal becomes equal to that of the polymer. Therefore, incident light passes through the PDLC device. Accordingly, the PDLC device is transparent when a voltage is applied thereto.
Due to the above-described properties, these PDLC devices may operate as an optical shutter without using a polarization plate. Recently, a technology of mixing a dye that absorbs light in a liquid crystal has been suggested to absorb dispersed light. When this technology is used, the PDLC becomes black when no voltage is applied thereto.